The reproductive system is a target of many chemicals that have wide-spread domestic, agricultural, or industrial use. While the mechanism of toxicity is unknown in most cases, it is apparent that the reproductive system of the male is sensitive to chemicals such as dibromochloropropane, the alkyl glycol ethers, and certain phthalate esters. The study of the mechanisms of reproductive toxicants is hampered by the complexity of the physiological and biochemical processes of spermatogenesis. However, the functional unit of the testes is the seminiferous tubule, and it is relatively easy to isolate and culture its primary cell types. This simplified system will be used to examine the effects of the chemicals listed above under the carefully controlled conditions of tissue culture. In brief, the objectives are: (1) to determine the toxic mechanism of three groups of reproductive toxicants by the use of isolated testicular cell and subcellular systems, and (2) to better understand the metabolism of the male reproductive system. Ultimately, the development of an in vitro system capable of assessing the potential reproductive toxicity of a chemical is envisioned.